Annex D (informative) Mapping from OPC A&E to OPC UA A&C ToC Previous Next

D.2 Alarms and Events COM UA wrapper ToC Previous Next

D.2.3 Event categories ToC Previous Next

Event Categories in the A&E COM Server are represented in the UA Server as ObjectTypes which are subtypes of BaseEventType. The BrowseName and DisplayName of the ObjectType Node for Simple and Tracking Event Types are constructed by appending the text ‘EventType’ to the Description of the Event Category. For Condition Event Types the text ‘AlarmType’ is appended to the Condition Name.

These ObjectType Nodes have a super type which depends on the A&E Event Type, the Event Category Description and the Condition Name; however, the best mapping requires knowledge of the semantics associated with the Event Categories and Condition Names. If an A&E COM UA Wrapper does not know these semantics then Simple Event Types are subtypes of BaseEventType, Tracking Event Types are subtypes of AuditEventType and Condition Event Types are subtypes of the AlarmType. Table D.1 defines mappings for a set of “well known” Category description and Condition Names to a standard super type.

Table D.1 – Mapping from standard Event categories to OPC UA Event types

COM A&E Event Type Category Description Condition Name OPC UA EventType
Simple -– -– BaseEventType
Simple Device Failure -– DeviceFailureEventType
Simple System Message -– SystemEventType
Tracking -– -– AuditEventType
Condition -– -– AlarmType
Condition Level -– LimitAlarmType
Condition Level PVLEVEL ExclusiveLevelAlarmType
Condition Level SPLEVEL ExclusiveLevelAlarmType
Condition Level HI HI NonExclusiveLevelAlarmType
Condition Level HI NonExclusiveLevelAlarmType
Condition Level LO NonExclusiveLevelAlarmType
Condition Level LO LO NonExclusiveLevelAlarmType
Condition Deviation -– NonExclusiveDeviationAlarmType
Condition Discrete -– DiscreteAlarmType
Condition Discrete CFN OffNormalAlarmType
Condition Discrete TRIP TripAlarmType

There is no generic mapping defined for A&E COM sub-Conditions. If an Event Category is mapped to a LimitAlarmType then the sub Condition name in the Event are be used to set the state of a suitable State Variable. For example, if the sub-Condition name is “HI HI” then that means the HighHigh state for the LimitAlarmType is active

For Condition Event Types the Event Category is also used to define subtypes of BaseConditionClassType.

Figure D.1 illustrates how ObjectType Nodes created from the Event Categories and Condition Names are placed in the standard OPC UA HasNotifier hierarchy.

readme_files/image035.png Figure D.1 – The type model of a wrapped COM AE server

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